3-Nitro-5-chloromethylsalicylaldehyde in the synthesis of photochromic spirochromenes of the indoline series

The nitration of 5-chloromethylsalicylaldehyde leads to 3-nitro-5-chloromethylsalicylaldehyde, the chlorine atom in which is smoothly replaced by a hydroxy or acetoxy group. The salicylaldehydes obtained condense with 1,3,3-trimethyl-2-methylene-indoline to give the corresponding photochromic indolinespirochromenes. The spectral-kinetics of the photochromic transformations of the spirochromenes are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 196–199, February, 1978.